During the oxidative degradation of 2,4-dimethylaniline (2,4-xylidine) by means of the H2O2/UV method, a series of hydroxylated aromatic amines are formed, this result confirming the role of the hydroxyl radical as an initiator of the oxidative chain reaction. Thermal or photochemically enhanced Fenton reactions in the presence of 2,4-dimethylaniline (2,4-xylidine) yield primarily 2,4-dimethylphenol as an intermediate product, the genesis of which may only be explained by an electron transfer mechanism. Experimental evidence for such a mechanism is presented, and values for the quantum yields of the photochemically enhanced reduction of iron(III) to iron(II) in aqueous solutions of 2,4-xylidine are given.

Novel heterogeneous photocatalysts were developed which are able to transfer electrons from excited Ru(II) donors within the zeolite framework to Co(III) acceptor complexes in the exterior. The materials were prepared and characterized by elemental analysis, electrochemical methods, diffuse reflectance, and raster and transmission electron microscopy. The catalysts consist of zeolite Y-encapsulated Ru(bpy) 3 2+ (bpy ) 2,2′bipyridine) sensitizers in close proximity to TiO 2 nanoparticles on the same support. The photophysical properties of Ru(bpy) 3 2+ within the zeolite supercages were investigated at different loadings of Ru(bpy) 3 2+ and TiO 2 . The photoexcited MLCT state of the zeolite-entrapped Ru(bpy) 3 2+ reacts via electron transfer with Co(dpphen) 3 3+ (dpphen ) 4,7-diphenyl-1,10-phenanthroline) in the exterior of the zeolite particles. The relative quenching of Ru(bpy) 3 2+ by external Co(dpphen) 3 3+ increases as the TiO 2 content within the zeolite is increased, where electron transfer from Ru(bpy) 3 2+ complexes within the interior of the zeolite are able to transfer electrons to Co(dpphen) 3 3+ . This observation indicates that electrons can be transported from the interior of the zeolite to the surface in the presence of an appropriate electron relay, such as TiO 2 nanoparticles.

Downsizing metal-organic framework (MOF) crystals into the nanoregime offers a promising approach to further benefit from their inherent versatile pore structures and surface reactivity. In this article, downsizing is referred to as the deliberate production of typical large MOF crystals into their nanosized versions. Here, we discuss various strategies towards the formation of crystals below 100 nm and their impact on the nano-MOF crystal properties. Strategies include an adjustment of the synthesis parameters (e.g., time, temperature, and heating rate), surface modification, ligand modulation, control of solvation during crystal growth and physical grinding methods. These approaches, which are categorized into bottom-up and top-down methods, are also critically discussed and linked to the kinetics of MOF formation as well as to the homogeneity of their size distribution and crystallinity. This collection of downsizing routes allows one to tailor features of MOFs, such as the morphology, size distribution, and pore accessibility, for a particular application. This review provides an outlook on the enhanced performance of downsized MOFs along with their potential use for both existing and novel applications in a variety of disciplines, such as medical, energy, and agricultural research.

A considerably arduous test of a novel class of composite materials consisting of [Ru(bpy)3]2+ and TiO2 codoped zeolites Y is presented here. The [Ru(bpy)3]2+ and TiO2 codoped zeolites Y served as photocatalysts in the oxidation of the model compounds 2,4-dimethylaniline (2,4-xylidine) by H2O2 in an acidic aqueous medium. Zeolite-embedded TiO2 (nano)particles play an important role in the degradation mechanism. The first step in this complex mechanism is the photoelectron transfer from photoexcited [Ru(bpy)3]2+*, located inside the supercage of zeolite Y, to a neighboring TiO2 nanoparticle. During this electron transfer process, electron injection into the conduction band of TiO2 is achieved. The second decisive step is the reaction of this electron with H2O2, which was previously chemisorbed at the surface-region of the TiO2 nanoparticles. In this reaction, a TiO2 bound hydroxyl radical (TiO2-HO.) is created. This highly reactive intermediate initiates then the oxidation of 2,4-xylidine, which enters the zeolites framework in its protonated form (Hxyl+). The formation of 2,4-dimethylphenol as first detectable reaction product indicated that this oxidation proceeds via an electron transfer mechanism. Furthermore, [Ru(bpy)3]3+, which was created in the initiating photoelectron transfer reaction between [Ru(bpy)3]2+* and TiO2, also takes place in the oxidation of Hxyl+. [Ru(bpy)3]2+ is recycled in that reaction, which also belongs to the group of electron transfer reactions. In addition to the primary steps of this particular Advanced Oxidation Process (AOP), the dependence of the efficiency of the 2,4-xylidine degradation as a function of the [Ru(bpy)3]2+ and TiO2 loadings of the zeolite Y framework is also reported here. The quenching of [Ru(bpy)3]2+* by H2O2 as well as the photocatalytic activity of the [Ru(bpy)3]2+ and TiO2 codoped zeolite Y catalysts both follow a distinct percolation behavior in dependence of their TiO2 content.

Titanium nitride/nitrogen-doped titanium oxide (TiN/N-doped TiO2) composite films were synthesized for visible light photodegradation applications. Thin films of TiN were sputter-deposited on precleaned glass substrates in an admixture of argon and nitrogen gases. The grown TiN films were subsequently oxidized in air at 350 °C at 15, 30, and 60 min. Raman spectral analysis revealed the formation of TiO2 with anatase structure at 15 min and transitioned to the rutile structure at longer oxidation times. X-ray photoelectron spectral analysis revealed the formation of N-doped TiO2 from the oxidized Ti. Visible light-induced photodegradation of methylene blue as test analyte showed 30% removal efficiency after exposure to visible light after 2.5 h. The highest degradation efficiency was observed when the anatase phase of TiO2 is the dominant phase in the film. Moreover, N-doping realized the visible light sensitivity of TiO2. This makes the composite film ideal for solar light-driven photodegradation of organic contaminants in wastewater.

This work demonstrates a simple, reproducible and scalable method of producing a potential slow-release fertilizer material. In this study, oxalate-phosphate-amine metal organic frameworks (OPA-MOFs) powder was synthesized from the hydrothermal treatment of ferric chloride (FeCl3•6H2O), orthophosphoric acid (H3PO4), oxalic acid dihydrate (H2C2O4•2H2O), and a common fertilizer, urea (CO(NH2)2). Being a structure directing agent (SDA)-type of MOF, the material is expected to slowly release urea via cation exchange, and eventually trigger the collapse of the framework, thus resulting to the subsequent release of the phosphates and iron-oxalate complexes. Elemental analysis revealed that the synthesized samples contains a promising amount of incorporated nitrogen and phosphorus. In this particular study, increasing in the amount of urea during the synthesis however revealed minimal change in the %N in the final product which tells us that maximum loading has already been achieved. P and N release experiments shall still be done bothinvitroand in actual soil samples to monitor the release delivery kinetics and efficiency of the OPA-MOFs for fertilizer release applications.

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